Electric discharges in gases



United atent fire 3,003,061 ELECTRIC DISCHARGES IN GASES Bernhard Berghaus and Hans Bucek, Zurich, Switzerland, assignors to Elektrophysikalische Anstalt Bernhard Berghaus, Vaduz, Liechtenstein Filed Apr. 1, 1957, Ser. No. 649,922 Claims priority, application Switzerland Apr. 2, 1956 13 Claims. (Cl. 250-495) The invention relates to a method of and apparatus for submitting substances in the gas or vapour and/ or liquid and/ or powdered solid state to metallurgical, chemical or other technical processes under the influence of electric discharges in gases. The method comprises introducing the substances in question into a reaction chamber which contains electrodes that are insulated from one another, through an element of the nature of a nozzle.

Such a method has already been described in our copending application Serial No. 506,752, filed May 9, 1955, now Patent No. 2,837,654, dated June 3, 1958. Experience subsequently gained in the course of the performance of the method has proved the principles and rules laid down therein to be correct. However, in the further development of the method and more particularly in the course of its large-scale industrial application to appropriate processes further discoveries have been made which are of considerable importance to the economic operation of a production plant of this kind. The original development of the method in the laboratory could not provide this insight because the basic problems arising in a laboratory are of a difierent kind. As will be hereinafter shown it was by no means obvious that the material problems which presented themselves in the industrial application of the method would be amenable to an economically acceptable solution at all.

A mode of solution of the problems encountered in practice is disclosed in the copending application of Bernhard Berghaus, Serial No. 671,790, filed July 15, 1957, and involves displacing the developing discharge along the gas stream in a direction away from the gas inlet.

The principal feature of the method proposed by the invention is the performance of a starting-up procedure which aims at concentrating the formation of the discharge in the discharge chamber in the immediate vicinity of the nozzle orifice through which the substances that are to be processed are inducted into the reaction chamber. To this end, prior to the commencement of admission of the substances for processing, a low-pressure atmosphere is created in the reaction chamber that will not impair the intended process, and potential is applied to the electrodes to induce a glow discharge of any size and extent on the parts that have an electric potential including the metal parts of the nozzle. Pressure is then raised to operational pressure which is above 50 mm. Hg and the voltage is adjusted until the discharge from the nozzle concentrates at the nozzle orifice within a spatial range that is particularly favoured by the relative position and conformation of the counter-electrode. This completes the the starting-up procedure and establishes the final permanent discharge conditions at which the substances for processing can be admitted through the nozzle at such a pressure that a zone of increased pressure will be produced in the reaction chamber in which the energy of discharge will be substantially concentrated.

Apparatus according to the invention for performing this method is characterized by a furnace chamber wholly enclosed within Walls adapted to be cooled, and by means for producing a reduced pressure therein for carrying out the starting-up procedure and for maintaining the operational pressure. There is further provided, in one of the Walls, at least one nozzle that is suitable for the intro-.

duction of the substances for processing and is likewise arranged to be cooled, as well as an insulated counterelectrode located opposite the nozzle orifice at such a distance and of such a surface conformation that a concentration of the discharge directly in front of the nozzle orifice during operation will be promoted. The substances for processing are conveyed to the nozzle by special means in the form of gases or vapours and/or of liquids and/ or powders at a pressure predetermined so as to bear a desired relation to the pressure in the interior of the furnace.

The invention will be hereinafter more particularly described with reference to an embodiment illustrated by the accompanying drawing which represents the lay-out in principle of apparatus according to the invention in diagrammatic form.

The method described in our above-mentioned Patent No. 2,837,654 can be performed with especial advantage from the point of view of the technique of creating electrical discharges in gases, within a pressure range between 1 and 10 mm. Hg because a small excess pressure of a gaseous substance introduced for processing through nozzles having a flow section of 1 sq. mm. will then create a. readily reproducible reaction zone which may have a length of say 200 mm. and a maximum diameter of 10 mm. The reaction vessel may be relatively small and consist for instance of an iron chamber 60 cms. in diameter and 100 cms. high, the dissipation of the generated heat creating no particular difiiculty. To maintain a low pressure of about 5-10 mm. Hg When the nozzle diameters are as stated suitable pumping means delivering say cubic metres per hour will be sufficient. However, the throughput in such a case will in magnitude be only of the order of 12 litres per minute.

Ina plant designed for industrial purposes it is principally the throughput that must be raised, and this calls for in increase in nozzle diameter or in the number of parallel working nozzles, a need which also arises in the processing of pulverised materials. It will be readily understood that the above mentionedpressure conditions, in which the pumping means must have a capacity that is equivalent to about a hundred times the quantity of gas introduced during the same period through the nozzle must rapidly lead to dimensions in the machinery required that cannot be accepted if the process is to be worked economically.

A careful study of the problems involved has, however, revealed a way of satisfactorily overcoming this difliculty and of making the method amenable to industrial application. As has already been described in our above-identified patent, the performance of the method requires the creation of a non-homogeneous pressure distribution inside the reaction chamber with a zone adjacent the nozzle orifice that exhibits a steep pressure gradient from the higher pressure immediately at the nozzle orifice to the lower pressure in the more remote interior. This zone represents the space in which the reactions take place and in which the substances for processing dwell for a certain length of time depending upon their rate of flow. However, it has been shown that the ratio between maximum and minimum pressure within the reaction zone is not as important as the concentration of the major portion of this pressure gradient within this zone. Consequently, in conformity with increasing eifective nozzle sections the pressure in the interior may be raised, preferably to over 20mm. Hg or even above 50 mm. Hg. If required, the pressure at which the substances for processing are forced through the nozzles may then likewise be increased. By reducing the under-pressure to between 20 and 50 mm. Hg or even more a considerably higher pump delivery and a correspondingly increased throughput can thus be achieved for the same expenditure in machinery.

This approach which is decisive for the applicability of the method in actual practice has led to the determination of the conditions for producing a high-energy discharge within a totally enclosed reaction chamber in which an operational pressure of over 20 mm. Hg is maintained by pumping means and into which the substances for processing are introduced in the form of gases, vapours, liquids or as finely divided powders with or without a carrier gas stream through a nozzle of arbitrary section at a correspondingly higher pressure. It has been ascertained that reliability of operation giving the desired high-energy and material yield can be achieved only if the desired discharge conditions are first established by a starting-up procedure.

This starting-up procedure is practically indispensable to the present method if a glow discharge of the desired type is to be produced at all. When the gas pressure is raised beyond 20 50 mm. Hg it becomes increasingly difiicult to initiate a glow discharge. Furthermore, conditions become practically incapable of control if the admission of the substances for processing at operational pressure has been already started before the electrical discharge has been established. It is in fact a necessity that the electric glow discharge inside the reaction chamber should be set up when the pressure distribution in the latter is still homogeneous and undisturbed. Moreover, the gas pressure should be in the range of about 1 to mm. Hg because within this pressure range a stable .glow discharge can be created without undue trouble. Attention must also be given to the fact that in such a reaction vessel the structural elements which carry an electric potential often have surfaces contaminated by impurities or other imperfections that impair the glow discharge. At such points a powerful thermal discharge develops when starting up and this may lead to undesirable local overheating. Moreover, occluded gas often erupts through metal surfaces and gives rise to considerable fluctuations in the current. To ensure a stable and undisturbed glow discharge from the cathodic structural elements the starting-up process must therefore be continued for a suitable length of time, say for 30 minutes, with as small as possible a turnover in energy.

The starting-up processalso permits the high-energy glow discharge to concentrate near the nozzle orifice or in the space in its immediate vicinity before the sub stances for processing are introduced through the nozzle. To this end the reaction chamber is evacuated to a pressure which is less than operationalpressure, i.e. to less than 20 mm. Hg gas pressure, before the substances in question are blown into the chamber. At the same time a gas atmosphere is introduced into the reaction chamber whichwill not impair the process that is to be subsequently performed, such as a rare gas atmosphere including for instance argon. However, other gases may also be used so long as they are of a kind that will not interfere with the subsequent reactions. The under-pressure is so determined that when applying a comparatively moderate continuous or alternating potential, preferably less than 1000 volts, an electric glow discharge will develop between the parts inside the reaction chamber that carry the potential. Within the stated pressure range the glow discharge is confined practically exclusively to the surface, or to the immediate vicinity thereof, of the metal parts that serve either permanently or temporarily as a cathode. At the beginning of the starting-up procedure the glow discharge on the cathodic members including the structural parts of the nozzle need not be limited in superficial extent.

Starting from this initial phase the gas pressure in the reaction chamber is then slowly raised and possibly the voltage varied to bring about a concentration of the discharge on the nozzle orifice and in its immediate vicinity. It has been found that in electrode arrangements which are fairly extensive in discharge equipment of the kind intended for industrial purposes, there is a well defined limiting voltage and a corresponding limiting gas pressure at which the cathodic or at least the temporary cathodic structural elements are still just completely covered by the high-energy glow discharge. If, as in the present case, it is desired that the discharge should cover these elements incompletely, that is to say that the discharge should be concentrated to certain members of the cathodic structural elements, then this can be achieved by increasing the pressure beyond this limiting pressure and/ or by reducing the voltage to values below the limiting voltage.

. The points of the cathode structure at which the discharge will then concentrate can be determined beforehand by suitably choosing the coordinated electrodes and by arranging their surface conformation and discharge gaps in such a Way that in operation the resistance along the discharge path will be particularly low between the said points on the cathode and the associated ring-like counter-electrode. The glow discharge will then tend to concentrate at these more favored points as soon as the limiting gas pressure has been exceeded and/or the voltage has been lowered below the limiting voltage.

In the present case the arrangement of the electrodes is so chosen that in operation the resistance along the discharge path will be lower from points at the nozzle orifice and its adjacent zone than at other points of the permanent or temporary cathodic structural members. When, after the glow discharge has started, the gas pressure inside the reaction chamber is increased continuously or in discrete steps until it approaches the operational pressure of over 20 mm. Hg, then the relative limiting gas pressure may be exceeded provided the electrode conformation is appropriate, and by then suitably adjusting the voltage below the limiting voltage the glow discharge will gradually contract more and more towards the more favoured points in the neighbourhood of the nozzle orifice. When the operational gas pressure has been reached, which may be as much as 250 mm. Hg or even more, a concentration within the more favoured zone around the nozzle orifice may then be achieved and the starting-up procedure thus concluded.

As the glow discharge concentrates, the energy density rises and considerable quantities of energy may be consumed even during the starting-up procedure and especially when approaching the final state. This will normally call for effective cooling of the nozzle and a good thermal conductivity of the latter near the orifice. When the nozzles according to the invention were cooled this was found to have a very favourable effect upon the desired phenomena which it has been impossible as yet satisfactorily to explain. Cooling of the nozzle or of the nozzle orifice appears to reduce the turnover in energy in the glow discharge at the surface of these parts in favour of an increase in the energy in the space in front of the nozzle, and this is very desirable for the purposes of the invention.

When the starting-up procedure has been concluded and the operational gas pressure in the reaction chamber has been reached the substances for processing can be introduced for instance in the form of a vapour jet or in the form of a carrier jet which entrains the substances that are to be processed in the form of a powder. At the same time suitable pumping means takes care of the maintenance of the required operational gas pressure in the reaction chamber. The substance introduced through the nozzle should be blown in at a pressure that exceeds the operational pressure sufiiciently to create a well-defined zone of raised pressure in which a major part of the pressure gradient is concentrated in the reaction space immediately adjacent the nozzle orifice. The arrangement of the electrodes in the reaction chamber is such that this zone of raised pressure will be located within the effective range of an electric field between the electrodes to which potential is applied. The electrode arrangement may be the same as that used for the startingup procedure or it may be some other electrode assembly and its source of power may be the same as or difier from that used for the starting-up procedure.

By the suitable determination of the pressure gradient in the reaction zone and by an appropriate adjustment of the electric field strength aifecting this zone a glow discharge engendered at the nozzle orifice can be made to expand to the whole or to predetermined parts of the zone of raised pressure so that the desired reaction between the substances that have been introduced will occur at these places. The nozzle orifice itself should be relieved of the load as far as may be possible.

It must be remembered that in the performance of the present method the nozzle constitutes one of the electrodes for the discharge in the reaction vessel and that it may form either the cathode or the anode if supplied with direct current. Nevertheless the method is not limited to this particular arrangement and the nozzle need not necessarily be in electrical communication with the sources of power. For instance, a separate anodic and cathodic electrode may be present and the substances for processing may be blown into the path of the discharge between these electrodes. In such a case it is not essential for the nozzle to be of metal and it may then conveniently consist of a refractory ceramic material.

Apparatus for performing the method according to the invention is diagrammatically illustrated by the accompanying drawing.

In said drawing,

FIG. 1 shows a glow discharge chamber, partly in section, with appurtenant structures constructed in accordance with the invention; while FIG. 2 is a diagram indicating the pressure conditions in the discharge chamber.

The furnace chamber 1 is enclosed on every side by metal walls 2 which are of hollow construction and adapted for the passage of a coolant in the direction of arrow 3 through their inside cavity 4. The interior 1 is closed at the top by an air-tight cover 5 consisting of an electrically insulating material with an admission element or nozzle 6 of metal embodying a duct 7 which ends inside the furnace 1 to form a nozzle 8. The wall which encloses the duct 7 and the nozzle 8 is provided with channels 9 and 10 for a coolant such as water or liquid air entering in direction 11 and, after flowing around the nozzle 8, leaving in direction 12. The joints between metallic parts and insulating material in the cover 5 are protected in a well-known manner by clearance gaps 13 and 14. Since the object here is, during the above described starting-up procedure, so far as possible to concentrate the glow d scharge on the edge of the nozzle orifice 8 located in the end portion 6a of the nozzle projecting into furnace chamber 1, and towards the inside of the chamber, ring-like counterelectrode 15a is arranged closely opposite the nozzle orifice, this ring being supported by part of the lead-in 16a which passes into the chamber through an insulated bushing 17a. The internal diameter of ring 15:: should be as small as possible but it should not in any way impede the gas jet projected from the nozzle orifice. In the illustrated example the lead-in is connected with the positive terminal of a source of potential 18, the negative terminal being connected with the induction element 6. The lead-in 16a is at the same time connected with one pole of another source of potential 19 for the supply for instance of an alternating potential, which has a centre tapping for a lead-in 16b passing through an insulating bushing 17b to a ring-like counterelectrode 1517, whereas the other pole is connected via a third lead-in 16c passing through insulating bushing 17c with a ring-like counterelectrode 15c.

Through a pipe 21 controlled by valve means the material to be processed, such asapowderedmlmstanceia nt tline 3 ia thedrawiege lhis zeeeisander thedireet element 6; To this end a finely dispersed suspension :of the powdered material which is fed through a hopper is produced in a mixer 22 by :a high-pressure current of gas which reaches an atomiser 24 through a pipe 23,, and the powdered material entrained by the carrier gas is then conveyed through pipe 21 to the nozzle 8 as soon as valve 20 has been opened. The pressure P can be read on a pressure gauge 26.

At the bottom end of the furnace chamber 1 is a suction pipe 27 which is connected through a stop valve 28 with the exhaust pumping set 29. This is rated to maintain in the furnace chamber 1 at the junction of the suction pipe 27 a pressure indication P on the pressure gauge 34 above 20 Hg, even though a gas stream is being injected through nozzle '8 at a pressure P The pressure ratio PIIPZ may be increased to high values.

'For carrying out the starting-up procedure, during which the two valves 20 and 28 are closed, an auxiliary gas may be inducted into the furnace chamber 1 through pipe 30 which joins pipe line 21, an exhaust pump 33 connected through a valve 32 with the pipe 27 being at the same time arranged to evacuate the furnace chamber to a vacuum corresponding-with a pressure P =l to 10 mm. Hg.

The final product produced in the furnace chain er may be removed continuously or intermittently through a discharging device equipped for instance with a gas trap 35 but which requires no detailed description in this context.

In the illustrated plant the starting-upprocedure during which the two valves 20 and 28 are closed therefore consists in first evacuating the furnace chamber 1 by means of exhaust pump 33 and in then introducing an auxiliary gas through pipe 30 and volume regulator or valve 31, such as a rare gas, until an auxiliary gas atmosphere which is free from undesirable impurities and which is at a pressure of l to 10 mm. Hg has been created. The circulation of a coolant through the induction element and the furnace walls 2 is then set in motion and a constant voltage of about 400400 volts is applied across the end of the'nozzle as the cathode and the electrode ring 15a as the anode. This sets up a glow discharge which at the stated gas pressure of l to 10 mm. Hg appears as a luminous skin on those metal parts of the nozzle which project freely from the protective clearance gap 13 into the furnace chamber 1. This glow discharge can now be concentrated on the edge of the nozzle orifice at 8 by increasing the volume of auxiliary gas inducted via valve 31 whilst maintaining pump 33 in operation and by thus gradually raising the pressureP until it approaches the operational pressure which in this instance is about 220 mm. Hg. Of course, the cross section of the nozzle maintains the volume of incoming gas at much too low a level to produce a non-homogeneous distribution of pressure inside the furnace chamber 1. As the pressure P rises and the glow discharge is more closely concentrated on the lip of the nozzle it is advisable to reduce the voltage from the source 18 to prevent too high a load per unit area at the nozzle end. When the operational pressure P =220 mm. Hg has been reached the discharge is fully concentrated in the immediate vicinity of the orifice of the nozzle 8;

The second source of potential 19 isnow brought into operation together with the main exhaust pump 29, and valve 28 is opened. Valve 29 is opened immediately afterwards to admit the current of carrier gas at the full pressure P which in the present case may be 5 atmospheres gauge, through the nozzle 8 into the furnace chamber 1. Adjacent the nozzle orifice a well-defined zone will then be formed in the furnace chamber 1 which incorporates the main part of the pressure gradient with isobars shaped approximately as delineated by the dotted entrained by a carrier gas, is supplied to the induction influence of the alternating electric field between the ring electrodes a and 15b and between 15b and 150 respectively, so that at least in certain regional shells within the range of the relative isobars an intense gas discharge, equivalent to a glow discharge, will be established and maintained in a stable condition. If the delivery of the main exhaust pump 29 is sufiicient, the pressure P can be maintained at a constant level so that with the simultaneous maintenance of an invariant pressure P the reaction zone will retain a constant size and the substances to be reacted will be unable to reach the interior of the furnace 1 otherwise than by passing through this zone.

The pressure drop in the discharge chamber 1 is illustrated by way of example in FIG. 2. The gas is supplied to the nozzle 6 at a substantially constant pressure, for example, 220 mm. Hg. From the nozzle mouth 8 to the counterelectrodes 150 the pressure falls rapidly along the line P P and then much more gradually to the exhaust.

In the illustrated embodiment the nozzle element 6 operates during the starting-up procedure as a cathode in conjunction with the electrode ring 15a. However, it is quite possible to operate ling 15d as the cathode in which case it is advisable to make provision for cooling the same to enable the ring to withstand the high energy load. Other electrode shapes than rings 15a, 15b, 150 could be employed. Moreover, the electrodes 15a, 15b and 15c could be operated with direct current. Since the temperatures of all the electrodes and of the nozzle orifice are very high, semi-conductor materials might be used for their construction instead of metals.

If desired the gradual rise in pressure during the starting-up procedure from a low initial pressure to operational pressure might be efiected via the admission nozzle 6. To

this end the valve means must be capable of sufficiently fine adjustment and a possibility must be provided of stopping the feed of material from the hopper and of collecting only carrier gas in the container 22. In such a case the admission elements 30, 31 for the special auxiliary gas may be omitted.

It will be seen from the foregoing that the present invention is concerned with a process by which it is made possible to create in the discharge chamber 1 an electrical discharge under predetermined pressure conditions and at a predetermined rate of energy utilization. The process consists in the feature that a starting procedure is carried out which begins with a small discharge energy and relatively low gas pressure, that is, under conditions which are easily controllable even when the voltage-carrying metallic parts which participate in the discharge contain initially certain impurities. This starting process of the invention makes it possible to apply and regulate practically any desired high discharge energy by step-bystep change of the gas pressure and of the energy supplied. Only when the desired energy in the discharge has been attained is the desired reaction carried out, at which time the substances to be reacted are charged into the chamber together.

In contrast to this, application Serial No. 671,790 is concerned with a process by which the relief of individual electrodes from excessive energy transformations thereat is made possible inside of the discharge space, a feature which is important, for example, for increasing the life span of the nozzle opening 8 in discharge processes with high energy conversion. If in such a case care is not taken that the energy density at the nozzle opening 8 is smaller than in the reaction zone inside of the discharge space 1, then there arises the danger that an unpermissible heating of the nozzle opening will occur which can lead to an excessively rapid wear of the nozzle.

As already mentioned, the above-described apparatus is suitable particularly for the carrying-out of chemical reactions in which it is of advantage if the reacting sub stances can react with each other only for a very short and predetermined time. In this way the result can be attained that dissociation of the produced reaction products is to a large extent prevented. For example, by introducing a current of air by way of the admission member 6 the result can be obtained that upon proper adjustment of the gas velocity and discharge energy, a gaseous reaction product N 0 is obtained with suppression of the otherwise produced compounds NO and N0 which usually arise in the treatment of air in a glow or are discharge. Also in the carrying out of nitrogenhydrogen reactions there can be obtained nitrogen-hydrogen compounds with the above described apparatus which. could not heretofore be produced or only with great difiiculty.

What we claim is:

1. In a method of submitting gases, vapors, dispersed liquids and powdered solid materials to metallurgical, chemical, or other technical processes under the influence of electric gas discharges by introducing them through elements of the nature of nozzles into a reaction chamber which contains electrodes that are electrically insulated from one another, a starting-up procedure for establishing a glow discharge in the reaction chamber concentrated in the immediate vicinity of the nozzle orifice, said starting-up procedure comprising the steps, prior to the admission of the substances for processing, of first creating a low pressure atmosphere which will not impair the intended processes in the reaction chamber, said pressure being below the operating pressure, applying potential to the electrodes to produce a glow discharge on the electrode or electrodes which at least temporarily carry a negative potential, then raising the pressure to an operational pressure in the range of 20 mm. Hg to several thousand mm. Hg and varying the potential drop until the discharge becomes concentrated in the vicinity of the nozzle orifice, whereupon the said starting-up procedure is concluded and a final state of the discharge established, and then introducing the substances for processing into the reaction chamber through the nozzle at a pressure which will produce a zone exhibiting a pressure gradient in which the energy of discharge is substantially concen trated.

2. A method as claimed in claim 1, characterised in that the gas pressure in the reaction chamber at the beginning of the starting-up procedure is arranged to be not more than 10 mm. Hg. i

3. A method as claimed of claim 1, characterised in that during the starting-up procedure the nozzle is operated at least temporarily as the cathode in supporting the glow discharge.

4. A method as claim in claim 1, characterised in that at least the orifice portion of the nozzle is cooled.

5. A method as claimed in claim 1, characterised in that at the end of the starting-up procedure and after the commencement of the introduction of substances for processing the power supply for the performance of the starting-up procedure is cut off as soon as the discharge phenomena have been established in the zone containing the pressure pradient.

6. Process according to claim 1, wherein the starting process is continued until the purifying action of the glow discharge has eliminated any impurities on the metal surfaces to which potential has been applied.

7. Process according to claim 6, wherein the applied voltage is higher than the ignition voltage but is lower than 1000 volts.

8. Apparatus for subjecting gases, vapors, dispersed liquids and powdered solid materials to metallurgical, chemical or other technical processes under the influence of electric gas discharges, comprising a furnace chamber wholly enclosed within walls, means for evacuating the chamber to a pressure below the operating pressure for conducting the starting-up procedure, means for maintaining the higher operational pressure, at least one admission element provided with a nozzle located in one of the walls for the introduction of substances forprocessing into the chamber, means for charging ac'oolant to the nozzle and withdrawing the same therefrom, at

least one insulated electrode located opposite the nozzle orifice at a distance therefrom and constructed and arranged to effect a concentration of the operational discharge phenomena directly in front of the nozzle orifice, means for conveying the substances for processing to the said nozzle at a pressure predetermined in relation to the pressure inside the furnace chamber, means for connecting the electrode to a source of electric power, an auxiliary exhaust pump which serves exclusively for evacuating the gas from the furnace chamber during the starting-up procedure, a main exhaust pump which serves to maintain the required gas pressure during operation, and means for connecting the pumps with, and for disconnecting the same from, the furnace chamber.

9. Apparatus for subjecting gases, vapors, dispersed liquids and powdered solid materials to metallurgical, chemical or other technical processes under the influence of electric gas discharges, comprising a furnace chamber wholly enclosed within walls, means for evacuating the chamber to a pressure below the operating pressure for conducting the starting-up procedura 'meaus formain taining the higher operational pressure, at least one admission elemcnt provided with a nozzle located in one of the walls for the introduction of substances for proc essing into the chamber, means for charging a coolant to the nozzle and withdrawing the same therefrom, at least one insulated electrode located opposite the nozzle orifice at a distance therefrom and constructed and arranged to effect a concentration of the operational discharge phenomena directly in front of the nozzle orifice, means for conveying the substances for processing to the said nozzle at a pressure predetermined in relation to the pressure inside the furnace chamber, means for connecting the electrode to a source of electric power, said admission element comprising an inner channel which discharges into the furnace chamber through the said nozzle, ducts surrounding the said channel and the nozzle for the passage of the coolant therethrough, and an insulator surrounding the admission element and protected by clearance gaps which communicate with the furnace interior from the metal of the furnace wall.

10. Apparatus for subjecting gases, vapors, dispersed liquids and powdered solid materials to metallurgical, chemical or other technical processes under the influence of electric gas discharges, comprising a furnace chamber wholly enclosed within walls, means for evacuating the chamber to a pressure below the operating pressure for conducting the starting-up procedure, means for maintaining the higher operational pressure, at least one admission element provided with a nozzle located in one of the walls for the introduction of substances for processing into the chamber, means for charging a coolant to the nozzle and withdrawing the same therefrom, at least one insulated electrode located opposite the nozzle orifice at a distance therefrom and constructed and arranged to effect a concentration of the operational discharge phenomena directly in front of the nozzle orifice, means for conveying the substances for processing to the said nozzle at a pressure predetermined in relation to the pressure inside the furnace chamber, and means for connecting the electrode to a source of electric power, at least that portion of the admission element which projects into the furnace interior consisting of metal.

11. A method as claimed in claim 1, wherein the zone which comprises the major part of the operational pressure gradient is subjected to the influence of an electric field and thereby excited to exhibit intense discharge phenomena, and wherein the substances for processing are injected into the reaction chamber transversely to the direction of the electric field.

12. Apparatus for subjecting gases, vapors, disposed and coaxiallyihe'rewith', but insulated from the admission 10 liquids and powdered solid materials to metallurgical, chemical or other technical processes under the influence of electric gas discharge, comprising a furnace chamber wholly enclosed within walls, means for evacuating the chamber to a pressure below the operating pressure for conducting the starting-up procedure, means for maintaining the higher operational pressure, at least one admission element provided with a nozzle located in one of the walls for the introduction of substances for processing into the chamber, means for charging a coolant to the nozzle and withdrawing the same therefrom, at least one insulated electrode located opposite the nozzle orifice at a distance therefrom and constructed and arranged to effect a concentration of the operational discharge phenomena directly in front of the nozzle orifice, means for conveying the substances for processing to the said nozzle at a pressure predetermined in relation to the pressure inside the furnace chamber, means for connecting the electrode to a source of electric power, a ring electrode located in close proximity to the nozzle orifice element and connected with one pole of a source of potential of which the other pole is connected with the nozzle, and additional ring electrodes arranged at a distance from the first electrode and coaxially therewith, the said electrodes being electrically insulated from one another though interconnected through a source of potential.

13. Apparatus for subjecting gases, vapors, dispersed liquids and powdered solid materials to metallurgical, chemical or other technical processes under the influence of electric gas discharges, comprising a furnace chamber wholly enclosed within walls, means for evacuating the chamber to a pressure below the operating pressure for conducting the starting-up procedure, means for maintaining the higher operational pressure, at least one admission element provided with a nozzle located in one of the Walls for the introduction of substances for proces'sing into the chamber, means for charging a coolant to the nozzle and withdrawing the same therefrom, at least one insulated electrode located opposite the nozzle orifice at a distance therefrom and constructed and arranged to effect a concentration of the operational discharge phenomena directly in front of the nozzle orifice, means for conveying the substances for processing to the said nozzle at a pressure predetermined in relation to the pressure inside the furnace chamber, means for connecting the electrode to a source of electric power, an auxiliary exhaust pump which serves exclusively for evacuating the gas from the furnace chamber during the starting-up procedure, a main exhaust pump which serves to maintain the required gas pressure during operation, means for connecting the pumps with, and for disconnecting the same from, the furnace chamber, and gas charging equipment including a volume regulator for the introduction of an auxiliary gas into the furnace chamber for establishing therein an initial gas atmosphere at a pressure between 1 and 10 mm Hg, and for raising the said pressure to the level of a predetermined operational pressure.

References Cited in the file of this patent UNITED STATES PATENTS Berghaus et a1. June 3, 1958 

